Process for evaluating speech quality in speech synthesis

Abstract: The present invention relates to a process for evaluating speech quality in speech synthesizers with the aid of a speech recognition system. The recognition system is programmed using a number of persons. It then receives synthetic or natural speech from speech synthesizers or persons respectively, displaying differing speech quality. The speech recognition system determines a level of recognition for each received speech quality. In order to evaluate the speech quality in a speech synthesizer, speech is received from the synthesizer by the speech recognition system, is allocated a level of recognition and is ranked in comparison to the levels of recognition for previously received speech.

Description: FIELD OF THE INVENTION The present invention relates to a process for evaluating speech quality in speech synthesis. More specifically, the invention is intended for use in equipment which is capable of receiving and analyzing speech messages, especially from speech synthesizers, i.e. text-to-speech converters. With the aid of the invention, the level of recognition of received speech in a speech recognition system can be ranked in terms of quality. PRIOR ART Speech recognition and text-to-speech conversion are techniques which are known per se. U.S. 5.127.055 relates to speech recognition. A large number of references, representing vocal expression, are stored. Each reference has an associated quality value representing the effectiveness with which an incoming vocal expression is recognized. The user can make corrections, which represent the accuracy in the speech recognition. The quality values are updated. U.S. 4.692.941 describes a known technique for text-to-speech conversion. The present invention solves, in a new way, the problem of analyzing speech quality in a speech synthesizer. SUMMARY OF THE INVENTION Present invention is defined of patent Claim 1. The present invention thus provides a synthezised speech quality evaluation process for analyzing speech quality in speech synthesis. According to the invention, a speech recognition system is trained using speech from a number of persons. The speech recognition system then receives synthetic or natural speech from speech synthesizers and persons respectively, displaying differing speech quality, and determines a level of recognition for each received speech quality. The speech quality for the speech synthesizer to be evaluated is determined by receiving speech from the speech synthesizer, determining its level of recognition and ranking the synthesizer in comparison with the levels of recognition for previously received speech speech syntesizers and persons. The invention is defined in the following patent claims. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The invention is intended for application in speech recognition systems which are to receive and analyze speech messages, especially from speech synthesizers. A speech recognition system must first be programmed to be able to recognize speech. Speech from a number of persons is used to teach the speech recognition system to recognize speech. The level of recognition for the speech from the programming group is consequently 100 %. When the speech recognition system is then used with general speech, it is able to understand the received speech to a very high degree. In order to assign a quality measure to received speech, the speech recognition system must receive speech from persons and speech synthesizers other than those which are used to program the speech recognition system. The speech quality from speech from different sources can be allocated certain speech quality values in dependence upon the associated level of recognition. This collective material can then be used to evaluate the speech quality in other speech synthesizers, for example. In order to evaluate the speech quality in a speech synthesizer, speech is sent from the synthesizer to the speech recognition system. This analyzes the speech and allocates a level of recognition to the received speech. This level of recognition can then be compared with speech previously received by the speech recognition system and ranked. A verdict can thus directly be given on the speech quality in the synthesizer in question; it is better than certain previously tested synthesizers and persons, but worse than others. The scope of the invention is limited only by the following patent claims.

Claims: Synthesized speech quality evaluation process, characterized in that a speech recognition system is trained using speech from a number of persons, in that the speech recognition system receives synthetic or natural speech from speech synthesizers and persons respectively, displaying differing speech quality, in that the speech recognition system determines a level of recognition for each received speech quality, in that speech from a speech synthesizer to be evaluated is received by the speech recognition system, is allocated a level of recognition and is ranked in comparison with the levels of recognition of previously received speech from said speech synthesizers and persons.

Inventors: LYBERG BERTIL, LYBERG, BERTIL
Applicants: TELIA AB
Application year: 1994
Main classification: G10L3
IPC codes: G10L15, G10L13, G10L11